Do you have a Covid Booster? You probably won’t need another one for a long time

Researchers showed last year that the elite school inside the lymph nodes where B cells train, called the germinal center, remains active for at least 15 weeks after the second dose of a vaccine Covid. In an updated study published in the journal Nature, the same team showed that six months after vaccination, memory B cells continue to mature and the antibodies they produce continue to acquire the ability to recognize new variants. .

“These antibodies at six months are better binders and stronger neutralizers than those produced one month after vaccination,” said Ali Ellebedy, an immunologist at Washington University in St. Louis who led the study.

In the latest study, another team showed that a third injection creates an even richer pool of B cells than the second injection, and the antibodies they produce recognize a wider range of variants. In laboratory experiments, these antibodies were able to repel Beta, Delta, and Omicron variants. In fact, more than half of the antibodies seen one month after a third dose were able to neutralize Omicron, even though the vaccine was not designed for this variant, according to the study.

“If you got a third dose, you’re going to get a quick response that will have some specificity for Omicron, which is why people who got a third dose do so much better,” said Michel Nussenzweig. , a Rockefeller University immunologist who led the study.

Memory cells produced after infection with the coronavirus, rather than vaccines, appear less potent against the Omicron variant, according to a study published last month in Nature Medicine. The immunity generated by the infection “varies a lot, while the vaccine response is much more consistently good,” said Marcus Buggert, an immunologist at the Karolinska Institute in Sweden who led the study.

Although most people, vaccinated or not, show only a small decline in their T-cell response against Omicron, about one in five showed “significant reductions in their responses” of about 60%, said Dr. Buggert. The differences are most likely due to their underlying genetic makeup, he said.

Yet recent studies suggest that in most people, the immunity gained through infection or vaccination will last a long time. Even if mutations in new variants alter some of the viral regions recognized by T cells, there would still be enough others to sustain a reasonably strong immune response, the experts said.

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